In medicine, scientific and technological developments for investigation and treatment are proceeding al an ever increasing rate. Protocols for patient management are becoming ever more complicated. Rational design an...
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In medicine, scientific and technological developments for investigation and treatment are proceeding al an ever increasing rate. Protocols for patient management are becoming ever more complicated. Rational design and scientific evaluation of protocols requires precise documentation. We propose a notation based on a series of simple flowcharts which describe procedures in increasing derail. Each step in a flowchart is justified by a reasoned argument, possibly including reference to published articles. General correctness requirements of a protocol include, for example, conformity with known indications and contraindications for investigations and treatments. These correctness requirements can be specified declaratively in mathematical logic and justified by reasoned argument. This makes the correspondence between a protocol and its scientific foundation even more explicit. Flowcharts of this nature are more easily created and modified using a personal computer. Furthermore, use of the computer enables a protocol to be checked automatically against its specification for more rapid identification of errors during development and maintenance of the protocol. We present the structured design of our flowcharting system in the 'Z' specification language, and we examine the practicality of our approach by means of a case study: the management of infertility. Our flowcharting system may also have application outside medicine where it is necessary to describe formal protocols for complex procedures.
Operations on action systems may be defined corresponding to CSP hiding and renaming. These are of particular use in describing the refinement between action systems in which the granularity of actions is altered. We ...
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As information systems become more complex, formal methods offer a solution to the increasing problem of ensuring correctness of design and implementation. This paper illustrates the use of mathematical specification ...
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Although many programming languages contain exception handling mechanisms, their formal treatment - necessary for rigorous development - can be complex. Nevertheless, this paper presents a simple incorporation of exit...
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In this paper, the Z notation is used to develop a small theory of terms and substitutions within which a simple unification algorithm can be specified and proved correct. Particular emphasis is placed on the use of Z...
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The computational requirements of modern information systems, coupled with the inherent limitations of the relational databases, are stimulating research into post-relational database systems. The recent advances in o...
The computational requirements of modern information systems, coupled with the inherent limitations of the relational databases, are stimulating research into post-relational database systems. The recent advances in object databases resulting from the integration of object-oriented programming capabilities with database capabilities, seem highly promising. The Object Database Management Group (ODMG) as part of the Object Management Group (OMG) has proposed a de facto standard known as ODMG-93 for object databases, which is rapidly gaining acceptance. The author introduces the relevant aspects of the object technology within the OMG framework, their Common Object Request Broker Architecture (CORBA), and discusses how this technology integrates with, and extends the client-server model. The author surveys the main elements of ODMG data model, particularly the datatypes supported, and introduces the elements of both, ODL (Object Definition Language) for defining the structure of the database, and OQL (Object Query Language) for defining queries over the database. Finally, some results are highlighted from the author's work on a calculus for the declarative representation of the OQL queries, suitable for an efficient implementation.
Most of the current exclusive-OR sum-of-products minimization algorithms use rule-based heuristics to transform an initial circuit description into a possibly compact form. This paper presents an enhanced minimization...
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Most of the current exclusive-OR sum-of-products minimization algorithms use rule-based heuristics to transform an initial circuit description into a possibly compact form. This paper presents an enhanced minimization algorithm, MINT, introducing new transformations including rules operating on three product terms at a time. These multiple-product-term transformations prove to be an efficient extension of previously defined two-product-term operating rules. Additionally, new efficient procedures for the optimization based on the use of don't cares are introduced. The algorithm can simplify multiple-valued input two-valued multiple-output incompletely specified functions.
This paper details the use of a circuit-based EM modelling technique combined with a harmonic balance simulator used to model the radiation from the microstrip bodies comprising an active antenna circuit. The modellin...
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This paper details the use of a circuit-based EM modelling technique combined with a harmonic balance simulator used to model the radiation from the microstrip bodies comprising an active antenna circuit. The modelling approach adopted for the planar bodies in the circuit will be shown to allow the use of concurrent algorithms in order to reduce overall computational time.
Acute abdominal pain is one of the most widely studied applications of computer-aided diagnosis. The usual approach is to apply Bayes' theorem with the assumption of conditional independence (''independenc...
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Acute abdominal pain is one of the most widely studied applications of computer-aided diagnosis. The usual approach is to apply Bayes' theorem with the assumption of conditional independence (''independence Bayes''). We compared various approaches to designing diagnostic programs for abdominal pain of suspected gynaecological origin. The methods range from statistical to knowledge-based. All programs were evaluated using a database of 1,270 cases collected retrospectively. Our results suggest that in this application no significant improvement in accuracy can be made by taking interactions into account, either by statistical or by knowledge-based means;independence Bayes is near-optimal. As far as accuracy is concerned, there appears to be little point in pursuing knowledge-based approaches. However, the ''nearest neighbours'' method using a new metric appears to be at least as accurate as independence Bayes. We argue that the nearest neighbours method is more suitable than independence Bayes for clinical use because of greater accountability.
We give a model-theoretic semantics for the logic of higher-order Horn clauses, the basis of a form of the lambdaProlog higher-order logic programming language. We define certain intensional general models and show th...
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We give a model-theoretic semantics for the logic of higher-order Horn clauses, the basis of a form of the lambdaProlog higher-order logic programming language. We define certain intensional general models and show that higher-order Horn clause logic is sound and complete with respect to them.
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